The invention relates generally to power-drive conveyors and, more particularly, to modular belt conveyors that articulate about a sprocket having an outer periphery that does not lie in a single plane normal to the axis of rotation of the sprocket.
Modular conveyor belts constructed of rows of plastic belt modules linked together at hinge joints by hinge pins are often used to convey meat, poultry, and other agricultural products. To comply with USDA and other sanitation requirements, belts in these applications must be cleaned continuously. The hinge joint between consecutive rows of belt modules is one of the most difficult areas to clean. Nooks and crannies in the hinge harbor bacteria shaded from cleaning water sprays. Furthermore, the teeth of conveyor drive sprockets compact fat, blood, and other debris into the hinge. As the belt articulates about sprockets on its transition from carryway to returnway, the hinges open to provide larger openings between the inner surface of the belt loop and the outer surface. For that reason, water sprays are often aimed at the underside of the hinge in the vicinity of the sprockets. Unfortunately, conventional sprockets shade the portions of the hinge along the lines of contact of the sprockets with the inner belt surface.
This problem has been addressed, for example, by the Kwik-Klean Belt Washer sold by Water Management Resources of O'Fallon, Ill., USA. In that device, a modular conveyor belt passes over and around at least one sprocket carried on a non-rotating hollow shaft. The motion of the belt causes the sprocket to rotate. The sprocket includes a first pair of diametrically opposed sectors and a second pair of diametrically opposed sectors that are laterally staggered in relation to the first pair of sectors. Each sprocket is flanked by a pair of nozzles, each of which produces a fan-shaped spray. The fan-shaped sprays overlap one another across the lateral extent of the belt so that the entire breadth of the belt is cleaned. The staggered sector design of the sprockets ensures that all sections of the belt are exposed to the spray. The nozzles are positioned to clean the hinges of the belt when they are open. But, because the hollow shaft is stationary, it cannot operate as a drive shaft.
Thus, there is a need for a conveyor whose hinges can be thoroughly cleaned at drive sprockets as well as at idler sprockets.